Liquid crystal display (LCD) panel substrates used in LCD apparatuses are formed by filling a gap between a pair of glass substrates with liquid crystals. A wiring line, a thin-film transistor (TFT) and the like are provided on one glass substrate, which is generally referred to as a TFT substrate. A color filter (CF) is provided on the other glass substrate, which is generally referred to as a CF substrate. Such a display panel substrate is, for example, formed by bonding a pair of mother glass substrates together and then cutting it into the size of the display panel substrate. A predetermined TFT, a wiring line and the like are provided in advance on the mother glass substrate to be formed into the TFT substrate.
FIG. 13 is a schematic perspective view of a cut display panel substrate. A TFT, a wiring line and the like are provided on a TFT substrate 11 (arranged in the lower part in FIG. 13) partially forming a display panel substrate 10. On one side of the TFT substrate 11, a terminal section 11a on which a plurality of terminals 11b are provided to be respectively connected to each wiring line is formed. A CF substrate 12 completing the formation of the display panel substrate 10 and the TFT substrate 11 are bonded with a predetermined gap to be filled with liquid crystals therebetween such that the terminal section 11a is exposed.
In the case of manufacturing the display panel substrate 10 having the structure described above, as shown in FIG. 14(a), the terminals 11b of the terminal section 11a provided on a TFT substrate 11A of a bonded glass substrate 10A are electrically connected to each other with a short link 11c provided on a side edge of the terminal section 11a of the TFT substrate 11A. The short link 11c prevents the accumulation of charge in each of the terminals 11b and the wiring lines and protects the wiring lines from electrostatic damage. After a plurality of bonded glass substrates 10A are cut from a bonded mother glass substrate for which a mother CF substrate and a mother TFT substrate are bonded, the TFT substrate 11A is cut along a cutting line 11d shown in FIG. 14(b), thus disengaging the connection of the terminals to each other 11b with the short link 11e (see FIG. 13). When the TFT substrate 11A is cut along the cutting line 11d, then the end face 11e extending along the cutting line 11d is ground and the both edges of the end face 11e are subjected to chamfering. In this case, in addition to the end face 11e along the terminal section 11a of the TFT substrate 11, at an end face where the terminal section of the display panel substrate 10 is not formed, the top edge of the CF substrate 12 and the bottom edge of the TFT substrate 11 are subjected to chamfering.
Each of the bonded glass substrates 10A is formed to respectively out a pair of bonded mother glass substrates. FIG. 15 shows a section view of the bonded glass substrate 10A cut from the bonded mother substrate. In this case, since a CF substrate 12A is cut so that the terminal section 11a provided on the TFT substrate 11A is exposed, the position of cutting the CF substrate 12A is different from the position of cutting the TFT substrate 11A. As shown in FIG. 15, the position of cutting the CF substrate 12A is adjacent to a sealing member 13 provided for bonding the TFT substrate 11A and the CP substrate 12A to each other. Therefore, while the CF substrate 12A is cut, the tension of the sealing member 13 is applied to an end face 12e of the CF substrate 12A to be cut, and as a result, the end face 12e to be cut may be gradually inclined (i.e., by hollowing out) toward the direction that approaches to the sealing member 13 as the end face 12e approaches to the sealing member 13, as indicated by dashed lines in FIG. 15.
In the case when the bonded glass substrate 10A is cut from a pair of mother glass substrates bonded to each other and when the terminal section 11a of the TFT substrate 11A is cut to remove the short link 11c from the bonded glass substrate 10A, an end face of the TFT substrate 11 or an end face of the CF substrate 12 of the cut display panel substrate 10 may cause chipping. If a relatively-large shell-shaped chipping occurs on the end face 11e adjacent to the terminal section 11a of the TFT substrate 11, the chipping may extend toward the inside of the TFT substrate over time and thus the terminals 11b provided on the terminal section 11a may be broken.
As such, if the display panel substrate 10 that is cut from a pair of mother glass substrates bonded to each other and that has a defect, such as a chipping, in the end face of the TFT substrate 11 or in the end face the CF substrate 12 is transferred to the next step to be formed into a liquid crystal display apparatus, the manufactured liquid crystal display apparatus may not operate properly, i.e., a defective product may be produced.
If a defective product is found in the last stage of manufacturing liquid crystal display apparatuses, there is a problem that the manufacturing yield of liquid crystal display apparatuses is significantly reduced. In particular, as described above, in a case where the end face 12e of the CF substrate 12 has been inclined, moisture may penetrate the gap between the inclined end face 12e and the TFT substrate 11 in a subsequent cleansing step. Thus the terminals 11b of the terminal section 11a of the TFT substrate 11 may be subjected to corrosion due to the moisture, thereby increasing the possibility of product defects.
In order to solve such problems, it is preferable that defects, such as an inclination of the end face, a chipping the end face and the like, be detected by inspecting the end face of the TFT substrate 11 or the end face of the CF substrate 12 in the display panel substrate 10 cut from the bonded mother substrate before the display panel substrate 10 is transferred to the next step. However, it is difficult to efficiently and accurately detect defect parts, such as the inclination of the end face, the chipping of end face and the like, of the display panel substrate 10.
Moreover, for the end face of the TFT substrate 11 and the end face of the CF substrate 12 in the display panel substrate 10, after the gap between the TFT substrate 11 and the CF substrate 12 is filled with liquid crystals, each of the edges of the end faces is generally subjected to chamfering by wet grinding process with grind stones. However, it is difficult to check whether a predetermined amount of the edges of the end faces are reliably subjected to chamfering.
The present invention is to solve such problems. The object of thereof is to provide an inspection apparatus and an inspection method capable of efficiently and accurately detecting a defect, such as chipping, for inspecting an end face of a transparent substrate and also capable of readily, for example, inspecting the state of a part subjected to chamfering of the end face.